Alkaline detergent having high contents of nonionic surfactant and complexing agent, and use of an amphoteric compound as solubilizer

ABSTRACT

The present invention relates to the use of an amphoteric compound as solubilizer and discloses an alkaline concentrate in the form of a clear aqueous solution which, after diluting with water, is suitable for use as detergent and which contains as least 4% by weight of a nonionic alkoxylate surfactant containing 2-12, preferably 3-10 alkyleneoxy groups having 2-4 carbon atoms, at least 50% of the alkyleneoxy groups being ethyleneoxy groups, at least 13% of a complexing agent, and 1-15% by weight of an amphoteric compound.

The present invention relates to an alkaline detergent concentrate withhigh contents of a nonionic surfactant and a complexing agent and in theform of a clear aqueous solution which, after diluting with water, issuitable for use as detergent for hard surfaces, dishwashing and textilewashing. As solubiliser, the concentrate contains an amphotericcompound.

It is generally desirable that concentrates of alkaline detergentcompositions can be produced in the form of clear solutions having highcontents of surfactants and complexing agents and/or alkali. Thus, it isknown from WO 93/23158 to solubilise alkaline detergent concentratescontaining 5% by weight of a nonionic surfactant by using a mixture of adimeric or oligomeric fatty acid and a C₆ -C₁₂ fatty acid assolubiliser. EP-A-105,063 discloses alkaline detergent compositions forhard surfaces, the compositions having high contents of surfactant andcomplexing agent. As solubiliser, use is made of water-soluble salts oflow-molecular organic acids, such as sodium or potassium salts oftoluene, benzene, cumene sulfonic acid and sodium and potassium salts ofsulfonsuccinic acid. In addition to the solubiliser, use is also made ofconventional organic solvents. U.S. Pat. No. 3,956,161 discloses the useof salts of a C₂₁ dicarboxylic acid as solubiliser for an alkalinenonionic detergent concentrate. U.S. Pat. No. 5,051,212 discloses adetergent composition for hard surfaces, containing 6-10% of asurfactant and 16-24% of a binary mixture of solvent and complexingagent. The solvent usually is a C₁ -C₃ alcohol, a C₆ -C₉ alkylaromatichydrocarbon or a diol having 6-16 carbon atoms. In all the examples, thegreater part of the surfactant is an anionic surfactant. In no case doesa nonionic surfactant constitute more than 2% of the concentrate. Othercommonly used solubilisers in detergent compositions are alkyl phosphatecompounds, amphoteric compounds or fatty alkyl aminoethoxylate having8-14 carbon atoms in the alkyl group. The publication 3rd CesioInternational Surfactants--a World Market; Proceedings Section D,Applications, pp 312-313, thus describes that amphoteric compounds havea solubilising effect on nonionic systems in concentrates with moderatecontents of both nonionic surfactant and complexing agent.

The object of the present invention is to be able to formulate analkaline detergent concentrate in the form of a clear solution in water.The concentrate should contain a very high content of nonionicsurfactant and complexing agent and should, after diluting with water,be suitable for use as detergent for, among other things, hard surfaces,dishwashing and textile washing. A further object is that theconcentrate has the form of a solution within a wide temperature range.Since concentrates having high contents of nonionic surfactant haveinverted solubility, i.e. the solubility decreases as the temperatureincreases, the concentrates should have the form of a clear solution, atleast up to 40° C., preferably up to 50° C., most advantageously up to80° C.

It has now surprisingly been found that the desiderata stated above canbe achieved by using as solubiliser an amphoteric compound as solubilitymediator. The alkaline concentrate according to the invention, which isin the form of a clear aqueous solution and which, after deluting withwater, is suitable for use as detergent, contains at least 4% by weightof a nonionic alkoxylate surfactant containing 2-12, preferably 3-10alkyleneoxy groups having 2-4 carbon atoms, at least 50% of thealkyleneoxy groups being ethyleneoxy groups, at least 13% by weight of acomplexing agent, and 1-15% by weight of an amphoteric compound havingthe formula ##STR1## wherein R₁ is a hydrocarbon group having 4-20carbon atoms, Z is the group CO, a group (B)_(n) OCH₂ CH(OH)CH₂, whereinB is an oxyalkylene group having 2-4 carbon atoms and n is from 0 to 5,or the group CH(OH)CH₂, z is 0 or 1, R₂ is the group --C₂ H₄ --, or thegroup --C₃ H₆ --, Y is hydrogen or a group R₃ COOM, y is 0-3, with theproviso that when z is 1 and Z is the group CO, y is 1-3, R₃ is --CH₂ --or --C₂ H₄ -- and M is hydrogen or a cation, as solubiliser. Theamphoteric compound having the formula (II) has a surprisingly goodsolubility and renders it possible to prepare concentrates which havethe form of a clear solution at temperatures in the range of 40-80° C.and which contain about 5% of a nonionic surfactant, and 40% by weightof a complexing agent or about 10% of a nonionic surfactant and 30% of acomplexing agent, while using a relatively small amount of thesolubiliser. Preferably, the amount of nonionic alkylate surfactant andcomplexing agent is at least 24% by weight of the concentrate.Consequently, the active contents in the concentrate may besignificantly increased as compared to prior art technique. It has alsobeen found that by the presence of the amphoteric compound, theconcentrates have a cleaning effect which is significantly better thancan be expected on the basis of the included nonionic alkoxylatesurfactant and the included complexing agent.

The nonionic alkoxylate surfactant may consist of compounds having theformula ##STR2## wherein R is a hydrocarbon having 8-18 carbon atoms, xis from 2 to 12, preferably 3-10, and A is an alkyleneoxy group having2-4 carbon atoms, the number of ethyleneoxy groups being at least 50% ofthe total number of alkyleneoxy groups.

The hydrophobic group R may thus be aromatic as well as aliphatic, andit may be branched or straight, saturated or unsaturated. Examples ofsuitable hydrocarbon groups are 2-ethylhexyl, octyl, decyl, cocoalkyl,lauryl, oleyl, rape alkyl, tallow alkyl, octylphenol and nonylphenol.Preferably, all alkyleneoxy groups are ethyleneoxy groups. The nonionicsurfactant having the formula (1a) can be prepared by reacting 2-12,preferably 3-10 mole ethylene oxide with 1 mole alcohol. Thealkoxylating can be carried out with ethylene oxide or by a mixture ofethylene oxide and higher alkylene oxide or by reacting ethylene oxideand higher alkylene oxide in blocks.

Preferably, the surfactant having the formula (Ia) is a compound inwhich an aliphatic alcohol having 8-14 carbon atoms is ethoxylated with3-6 mole ethylene oxide per mole alcohol, suitably in the presence of acatalyst, such as Ca(OH)₂, Ba(OH)₂, Sr(OH)₂ and hydrotalcite, whichgives a narrow distribution of ethylene oxide and low contents ofunreacted alcohol. If desired, it is possible, for the purpose ofobtaining lower foaming, after the ethoxylation to react for example 1or 2 mole propylene oxide or butylene oxide per mole ethoxylate. Thealiphatic alcohol having 8-14 carbon atoms preferably consists ofoxoalcohols, Guerbet alcohols, methyl-substituted alcohols with 2-4groups having the formula --CH(CH₃)-- included in the alkyl chain andstraight alcohols.

Other suitable nonionic alkoxylate surfactants are those having theformula ##STR3## wherein R is a hydrocarbon group or an acyl grouphaving 8-18 carbon atoms, A has the meaning stated in Formula (Ia), andx₁ and x₂ are, independently of each other, 0-12, the sum of x₁ and x₂being 2-12, preferably 3-10. The hydrocarbon group and the acyl groupcan be aromatic or aliphatic, or branched, saturated or unsaturated.Examples of suitable groups are 2-ethylhexyl, octyl, decyl, cocoalkyl,lauryl, oleyl, rape alkyl, tallow alkyl, octylphenol and nonylphenol andthe corresponding aliphatic acyl groups. Especially suitable hydrocarbongroups and acyl groups are those having 8-14 carbon atoms, obtained fromoxoalcohols, Guerbet alcohols, methyl-substituted alcohols with 2-4groups having the formula --CH(CH₃)-- included in the alkyl chain andstraight alcohols as well as the corresponding carboxylic acids. If R inthe formula (Ia) is an acyl group, preferably one of x₁ and x₂ is 0,whereas if R in the formula (Ib) is a hydrocarbon group, i.e. when thenitrogen atom is an amine nitrogen, x₁ and x₂ are both preferablydifferent from zero.

The amphoteric compund, which usually is 2-10% by weight of theconcentrate, preferably consists of compounds in which the number of R₃COOM groups is at least 2, M preferably being a monovalent cation, suchas an alkali ion or an organic ammonium ion. The designation ypreferably is 0-2. The hydrocarbon group R₁ preferably is an aliphaticgroup having 6-14 carbon atoms. If R₁ is a hydrocarbon group having morethan 14 carbon atoms, these are preferably unsaturated, aliphatichydrocarbon groups. Specific examples of suitable R₁ groups or R₁ COgroups are 2-ethylhexyl, octyl, 3-propylheptyl, decyl, dodecyl, oleyl,cocoalkyl and tallow alkyl and the corresponding acyl groups. Examplesof suitable amphoteric compounds are compounds having the formulae##STR4## wherein R₂, R₃, M and Y have the meaning stated in formula (II)and Y₁ is 0-2, preferably 0 or 1, the number of R₃ COOM groups being atleast 2, ##STR5## wherein R₂, R₃, Y and M have the meaning stated informula (II) and Y₂ is 0 or 1, the number of R₃ COOM groups being atleast 2, ##STR6## wherein R₂, R₃, Y and M have the meaning stated informula (II), and y₃ is 0-2, preferably 0 or 1, the number of R₃ COOMgroups being at least 2, ##STR7## wherein R₂, R₃, B, Y, M and n have themeaning stated in formula (II), and y₄ is 0-2, preferably 0 or 1, thenumber of R₃ COOM groups being at least 2. B is preferably anethyleneoxy group, and n is preferably 0 or 1.

The complexing agents in the concentrate can be inorganic as well asorganic. The inorganic complexing agents are mainly alkali salts ofsilicates and phosphates, such as sodium tripolyphosphate, sodiumorthophosphate, sodium pyrophosphate, sodium phosphate, polymer sodiumphosphates and the corresponding potassium salts. The organic complexingagents are mainly alkaline aminopolyphosphonates, organic phosphates,polycarboxylates, such as citrates, and aminocarboxylates. Examples ofaminocarboxylates are sodium nitrilotriacetate (NTA), sodiumethylenediaminetetraacetate (EDTA), sodiumdiethylenetriaminepentaacetate (DTPA), sodium1,3-propylenediaminetetraacetate (PDZ) and sodiumhydroxyethylethylenediaminetriacetate (HEDTA). The amount of complexingagents in the concentrate may be as high as 50%.

In addition to the nonionic alkoxylate surfactant, the complexing agentand the amphoteric solubilising compound, the concentrate may have anumber of different supplementary additives, such as anionicsurfactants, for example C₉ -C₁₆ -alkylbenzene sulphonates, C₉ -C₁₈-paraffin sulphonates, C₁₂ -C₁₈ -olefin sulphonates, C₁₀ -C₁₈ -alkylsulphates and soaps, amphoteric and zwitterionic surfactants, cationicsurfactants and nonionic surfactants other than the alkoxylatesdescribed above.

Other additives are thickening agents, such as polyacrylates,carboxymethylcellulose, methylhydroxyethylcellulose, methylcellulose,hydroxyethylcellulose, ethylhydroxyethylcellulose andmethylethylhydroxyethylcellulose, perfumes, colourants,reprecipitation-inhibiting agents, defrosting stabilisers, solvents,preservatives, pesticides etc.

The invention will now be described in more detail by means of theExamples below.

EXAMPLE 1

Different amounts of a solubiliser according to Table 1 were added toalkaline detergent compositions containing 5 alternatively 10% by weightof a nonionic surfactant, based on a tridecyl alcohol with which 10 moleethyleneoxide per mole alcohol had been reacted in the presence of KOHas catalyst, different amounts of tetrapotassium phosphate, trisodiumnitrilotriacetate and tetrasodium ethylenediaminetetraacetate, therebydetermining the clearness of the various compositions. The resultsobtained are shown in Tables 2 and 3.

                  TABLE 1                                                         ______________________________________                                        Amphotreric compound         Code                                             ______________________________________                                         ##STR8##                    1                                                 ##STR9##                    2                                                 ##STR10##                   3                                                 ##STR11##                   4                                                 ##STR12##                   5                                                 ##STR13##                   6                                                 ##STR14##                   7                                                 ##STR15##                   8                                                 ##STR16##                   9                                                 ##STR17##                   A                                                wherein t + r = 15                                                            Cumene sulphonate            B                                                ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        5% Nonionic surfactant                                                        Solubiliser                     Clearness                                     Code      %      TKPP      NTA  EDTA    ° C.                           ______________________________________                                        1         8.0    20                     80                                    1         7.2              30           50                                    1         7.2                   30      50                                    2         3.9    20                     >80                                   2         3.0              25           70                                    2         6.0                   30      58                                    3         3.5    20                     80                                    3         3.3              30           60                                    3         6.0                   35      60                                    4         8.0    20                     80                                    4         5.2              20           60                                    4         5.2                   20      60                                    5         5.6    20                     >80                                   5         6.0              20           75                                    5         6.0                   20      75                                    6         6.8    20                     >80                                   6         5.2              20           80                                    6         6.8                   25      42                                    7         5.4              25           >80                                   8         7.8              30           40                                    9         9.0              35           60                                    A         20     20                     Turbid                                A         20               20           Turbid                                A         20                    20      Turbid                                B         8.0    20                     Turbid                                B         6.0              20           70                                    B         6.0                   20      70                                    ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        10% Nonionic surfactant                                                       Solubiliser                     Clearness                                     Code      %      TKPP      NTA  EDTA    ° C.                           ______________________________________                                        1         7.6    15                     >80                                   1         8.0              25           55                                    1         8.0                   25      55                                    2         4.8    15                     >80                                   2         3.6              20           55                                    2         3.6                   20      55                                    3         5.4    15                     75                                    3         4.5              20           40                                    3         4.5                   20      40                                    4         7.2    15                     70                                    4         7.2              20           40                                    4         7.2                   20      40                                    5         8.0    15                     >80                                   5         4.0              15           40                                    5         4.0                   15      40                                    6         7.6    15                     >80                                   6         4.0              15           45                                    6         3.6                   15      42                                    7         5.4              25           >80                                   8         7.8              25           45                                    9         9.0              25           55                                    A         20     15                     Turbid                                A         20               15           Turbid                                A         20                    15      Turbid                                B         10     15                     Turbid                                B         7.2              15           40                                    B         7.2                   15      40                                    ______________________________________                                    

The inventive solubilisers showed an enhanced ability of solubilisinglarge amounts of a nonionic surfactant in combination with a complexingagent as compared to the amine ethoxylate and the cumene sulphonate.

EXAMPLE 2

Different amounts of a solubiliser according to Table (I) were added toalkaline detergent compositions containing 5 alternatively 10% by weightof a nonionic surfactant, based on a synthetic primary C₉₋₁₁ alcoholhaving a linearity of above 80% by weight with which 5 mole ethyleneoxide per mole alcohol had been reacted in the presence of Ca(OH)₂, i.e.a narrow-range-catalyst, different amounts of tetrapotassium phosphate,trisodium nitrilotriacetate and tetrasodium ethylenediaminetetraacetate,thereby determining the clearness of the different compositions. Theresults obtained are shown in Tables 4 and 5.

                  TABLE 4                                                         ______________________________________                                        5% Nonionic surfactant                                                        Solubiliser                     Clearness                                     Code      %      TKPP      NTA  EDTA    ° C.                           ______________________________________                                        1         6.0    30                     80                                    1         6.0              40           50                                    1         6.0                   50      80                                    2         6.0    30                     80                                    2         6.0              35           >80                                   2         6.0                   40      >80                                   5         12.0                  35      >80                                   5         8.0              25           >80                                   6         7.2    20                     80                                    7         4.6              35           >80                                   8         6.7              30           45                                    9         5.7              35           >80                                   A         20     20                     Turbid                                A         20               20           Turbid                                A         20                    20      Turbid                                B         8.0    20                     Turbid                                B         6.8              25           80                                    B         8.0                   30      80                                    ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        10% Nonionic surfactant                                                       Solubiliser                     Clearness                                     Code      %      TKPP      NTA  EDTA    ° C.                           ______________________________________                                        1         8.0    20                     50                                    1         6.8              35           45                                    1         7.6                   40      45                                    7         3.8              25           >80                                   8         6.7              30           45                                    9         9.0              30           80                                    A         5.0              10           40                                    A         12.0                  15      40                                    B         5.6    10                     Turbid                                B         6.4              15           50                                    B         6.0                   15      50                                    ______________________________________                                    

As is evident from the results, the amphoteric compounds, withoutexception, were at least equivalent to or better than the referenceproducts as solubiliser.

EXAMPLE 3

White lacquered metal plates were soiled with an oil black mixtureobtained from diesel engines. The reflectance of the metal plates wasmeasured by means of a colour reflectometer Minolta Chroma Meters CR-200before and after cleaning with two different alkaline detergents of thefollowing composition.

                  TABLE 6                                                         ______________________________________                                                         Composition, % by weight                                     Component          I         II                                               ______________________________________                                        Nonionic surfactant (Example 2)                                                                  5         5                                                NTA                25        25                                               Amphoteric compound 1                                                                            3.2       --                                               Cumene sulphonate  --        6.8.sup.1)                                       Water              balance   balance                                          ______________________________________                                         .sup.1) This amount was necessary to obtain a clear solution.            

One part by weight of the compositions was diluted with 20 parts byweight of water, and the diluted solutions were applied on the metalplates and washed away with tap water after 40 seconds. The washed-awaysoil was calculated by the computer program integrated in the meter,whereby for composition I according to the invention about 69%washed-away soil and for the reference product about 57% was obtained,although the amount of cumene sulphonate in composition II was 6.8% ascompared to 3.2% amphoteric compound in composition I.

What is claimed is:
 1. An alkaline concentrate in the form of a clearaqueous solution which, after dilution with water, is suitable for useas detergent, said concentrate comprising at least 4% by weight of anonionic alkoxylate surfactant, which contains 2-12, alkyleneoxy groupshaving 2-4 carbon atoms, at least 50% of the alkyleneoxy groups beingethyleneoxy groups, at least 13% by weight of a complexing agent, thetotal amount of the nonionic alkoxylate surfactant and the complexingagent being at least 24% by weight, and 1-15% by weight of an amphotericcompound having the formula ##STR18## wherein R₁ is a hydrocarbon grouphaving 4-20 carbon atoms, Z is the group CO, a group (B)_(n) OCH₂CH(OH)CH₂, wherein B is an oxyalkylene group having 2-4 carbon atoms andn is from 0 to 5, or the group CH(OH)CH₂, z is 0 or 1, R₂ is the group--C₂ H₄ --, or the group --C₃ H₆ --, Y is hydrogen or a group R₃ COOM, yis 0-3, with the proviso that when z is 1 and Z is the group CO, y is1-3, R₃ is --CH₂ -- or --C₂ H₄ -- and M is hydrogen or a cation, assolubiliser.
 2. The concentrate of claim 1, wherein the nonionicalkoxylate surfactant consists of compounds having the formula ##STR19##wherein R is a hydrocarbon having 8-18 carbon atoms, x is from 2 to 12and A is an alkyleneoxy group having 2-4 carbon atoms, the number ofethyleneoxy groups being at least 50% of the total number of alkyleneoxygroups.
 3. The concentrate of claim 1, wherein the nonionic alkoxylatesurfactant has the formula ##STR20## wherein R is a hydrocarbon group oran acyl group having 8-18 carbon atoms, A has the meaning stated informula (Ia), and x₁ and x₂ are, independently of each other, 0-12, thesum of x₁ and x₂ being 2-12.
 4. The concentrate of claim 3, wherein R isacyl and one of x₁ and x₂ is
 0. 5. The concentrate of claim 1 whereinthe amphoteric compound has the formula ##STR21## wherein R₂, R₃, M andY have the meaning stated in formula (II) and y₁ is 0-2, the number ofR₃ COOM groups being at least
 2. 6. The concentrate of claim 1 whereinthe amphoteric compound has the formula ##STR22## wherein R₂, R₃, Y andM have the meaning stated in formula (II) and y₂ is 0 or 1, the numberof R₃ COOM groups being at least
 2. 7. The concentrate of claim 1,wherein the amphoteric compound has the formula ##STR23## wherein R₂,R₃, Y and M have the meaning stated in formula (II) and y₃ is 0-2, thenumber of R₃ COOM groups being at least
 2. 8. The concentrate of claim 1wherein the amphoteric compound has the formula ##STR24## wherein R₂,R₃, B, Y, M and n have the meaning stated in formula (II) and y₄ is 0-2,the number of R₃ COOM groups being at least
 2. 9. The concentrate ofclaim 1 wherein the complexing agents are inorganic phosphates oraminocarboxylates.
 10. The concentrate of claim 9 wherein the complexingagents are sodium nitrilotriacetate (NTA), sodiumethlenediaminetetraacetate (EDTA), sodium diethylenetriaminepentaacetate(DTPA), sodium 1,3-propylenediaminetetraacetate (PDZ) and sodiumhydroxyethylethlenediaminetriacetate (HEDTA).
 11. A method ofsolubilizing an alkaline aqueous detergent concentrate to form a clearaqueous solution, said detergent concentrate containing at least 4% byweight of a nonionic alkoxylate surfactant which contains 2-12alkyleneoxy groups having 2-4 carbon atoms, at least 50% of thealkleneoxy groups being ethyleneoxy groups, and at least 13% by weightof a complexing agent, said method comprising adding to said detergentconcentrate from 1-15% by wieght of an amphoteric compound having theformula ##STR25## wherein R₁ is a hydrocarbon group having 4-20 carbonatoms, Z is the group CO, a group (B)_(n) OCH₂ CH(OH)CH₂, wherein B isan oxyalkylene group having 2-4 carbon atoms and n is from 0 to 5, orthe group CH(OH)CH₂, z is 0 or 1, R₂ is the group --C₂ H₄ --, or thegroup --C₃ H₆ --, Y is a group R₃ COOM, y is 0-3, with the proviso thatwhen z is 1 and Z is the group CO, y is 1-3, R₃ is --CH₂ -- or --C₂ H₄-- and M is hydrogen or a cation.
 12. The concentrate of claim 3 whereinx₂ is 3-10.
 13. The concentrate of claim 5 wherein y₁ is 1 or
 0. 14. Theconcentrate of claim 7 wherein y₁ is 0 or
 1. 15. The concentrate ofclaim 8 wherein y₄ is 1 or
 0. 16. The concentrate of claim 2 wherein xis 3-10.
 17. The concentrate of claim 3 wherein R is a hydrocarbon groupand x₁ and x₂ are both different.
 18. The concentrate of claim 1 whereinsaid nonionic alkoxylate surfactant contains 3-10 alkyleneoxy groups.19. The concentrate of claim 1, wherein R₁ is a hydrocarbon group having6-14 carbon atoms.
 20. The concentrate of claim 1, wherein the amount ofwater in the concentrate makes up the remainder thereof.
 21. The methodof claim 12, wherein R₁ is a hydrocarbon group having 6-14 carbon atoms.22. The method of claim 12, wherein the amount of water in theconcentrate makes up the remainder thereof.